As means for directly converting chemical energy to electrical energy, there is a battery. Since utilizing electrochemical change, the battery performs action of discharge of electrical charge or repeating of charge and the discharge of the electrical charge, the battery is used as a power source for a variety of electrical and electronic apparatuses. In addition, as means for performing the action of the repeating of charge and discharge of the electrical charge, there is a capacitor (condenser). The capacitor is used as an electrical component of a variety electrical and electronic apparatuses.
In recent years, as a secondary battery having a high energy efficiency, a lithium-ion battery, a lithium-ion polymer battery, or the like is used as a power source of a mobile telephone, a personal computer, a camera, or the like. In addition, using a fuel cell as a power source of a car has been tried. Regarding a solar cell, the development of a dye sensitized solar cell, as the next-generation of a crystal solar cell, an amorphous solar cell, and a thin-film solar cell, which allows low-cost widespread use is progressing.
For example, in the fuel cell, a negative electrode material obtained by coating, with an active material of a carbon material, a surface of a current collector formed of an aluminum plate is used.
In the dye sensitized solar cell, an electrode material obtained by coating, with an electrically conductive material such as a carbon material, a surface of a thin film base material is used.
On the other hand, in an electric double layer capacitor which is one of electrochemical capacitors, a polarized electrode obtained by coating, with an active material of an activated carbon powder, a surface of a current collector formed of aluminum foil is used. Specifically, for example, Japanese Patent Application Laid-Open Publication No. 10-64765 (Patent Literature 1) discloses that a binder, an electrical conducting material, and the like are added to the activated carbon powder, are mixed therewith, and are prepared so as to be in a slurry state, and the resultant is applied onto a surface of the aluminum foil and thereafter, is dried at a room temperature, and the resultant is cut so as to have a predetermined size, thereby manufacturing the polarized electrode. In addition, there is a case where a mixture of the activated carbon powder, a resin, and the like is bonded onto a surface of the aluminum foil through thermocompression, thereby manufacturing the polarized electrode.
In an electrolytic capacitor, conventionally, an electric conductor constituted of aluminum foil whose surface area is enlarged through etching has been used as a cathode material. In recent years, a cathode material whose electrode surface is enlarged by attaching a carbon powder onto a surface of aluminum foil has been developed.
The above-mentioned carbon coated aluminum material coated with the active material of the carbon material is manufactured by employing a method in which the carbon material is attached thereonto simply by using a binder. Therefore, manufacturing steps are comparatively easy. However, when it is assumed that the carbon coated aluminum material is used as a constituent material of an electronic component such as an electrode material for a long period of time, there arises a problem in that properties of the carbon coated aluminum material are deteriorated due to heat generated from the electronic component.
In addition, for the purpose of enhancing productivity of a circuit assembly line, an electronic component tends to be a surface-mounted component (Surface Mounted Device). In this case, since the attachment of the electronic component is conducted by employing a reflow method, it is required to maintain the properties of the carbon coated aluminum material even under a harsh temperature condition. In relation to the above-mentioned requirement, since in the carbon coated aluminum material in which the carbon material is attached thereto by using the conventional binder, the binder itself is unstable with respect to heat in general, and through the application of heat, adhesiveness between the carbon material and a surface of the aluminum material becomes weak due to the deterioration of the binder, finally, falling-off of the carbon material may occur. In addition, it has been pointed out since before that if an added amount of the binder is increased in order to enhance the adhesiveness between the carbon material and the surface of the aluminum material, it is likely that a value of resistance is increased due to the presence of the binder or a fluctuation in the value of resistance occurs due to the change of properties of the binder caused by the heat. As described above, when in the carbon coated aluminum material, the binder is used in order to attach the carbon material onto the surface of the aluminum material, there arise many problems.
On the other hand, for example, as disclosed in International Publication No. WO2004/087984 (Patent Literature 2), a carbon coated aluminum material, which includes an aluminum material and a carbon-containing layer formed on a surface of the aluminum material and further includes an interposing layer formed between this aluminum material and the carbon-containing layer and including an aluminum element and a carbon element, has been developed. In this carbon coated aluminum material, the interposing layer formed between the aluminum material and the carbon-containing layer as an active material layer acts to enhance the adhesiveness between the aluminum material and the active material layer. Therefore, the problem in that through the application of heat, the adhesiveness between the carbon-containing layer and the surface of the aluminum material becomes weak is solved. In addition, even if the binder is used as one of the starting materials of the carbon-containing layer, since heat is applied in order to form the carbon-containing layer, the binder has been vanished. Accordingly, the problem of a reduction in the adhesiveness, resulting from the deterioration of the binder due to the heat as described above, does not arise.